{"id":"CVE-2026-49852","summary":"joserfc: HS256/HS384/HS512 verify accepts empty/nil HMAC key (cross-language sibling of CVE-2026-45363)","details":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.6.8, joserfc.jwt.decode accepts attacker-forged HMAC-signed tokens when the caller-supplied verification key is the empty string or None, because HMACAlgorithm.sign and HMACAlgorithm.verify in src/joserfc/_rfc7518/jws_algs.py pass the output of OctKey.get_op_key(...) to hmac.new(...) and OctKey.import_key in src/joserfc/_rfc7518/oct_key.py only emits a SecurityWarning for keys shorter than 14 bytes without rejecting zero-length input. This issue is fixed in version 1.6.8.","aliases":["GHSA-gg9x-qcx2-xmrh","PYSEC-2026-2528"],"modified":"2026-07-25T03:56:24.712411809Z","published":"2026-07-17T19:14:58.019Z","related":["CGA-8hcq-26qx-894x","openSUSE-SU-2026:11183-1","openSUSE-SU-2026:21263-1"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-1391","CWE-287","CWE-326"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49852.json"},"references":[{"type":"WEB","url":"https://github.com/authlib/joserfc/releases/tag/1.6.8"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49852.json"},{"type":"ADVISORY","url":"https://github.com/authlib/joserfc/security/advisories/GHSA-gg9x-qcx2-xmrh"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49852"},{"type":"FIX","url":"https://github.com/authlib/joserfc/commit/86d00910b2b2d2d07503fee9b572906daefab7f1"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/authlib/joserfc","events":[{"introduced":"0"},{"fixed":"86d00910b2b2d2d07503fee9b572906daefab7f1"},{"fixed":"ea1d9e301cc3f6d20d141058e4a0c4befc599b62"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"1.6.8"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["1.6.7","1.6.5","1.6.4","1.6.3","1.6.2","1.6.1","1.6.0","1.5.0","1.4.3","1.4.1","1.4.0","1.3.3","1.3.2","1.3.1","1.3.0","1.2.2","1.2.1","1.2.0","1.1.0","1.0.4","1.0.3","1.0.2","1.0.1","1.0.0","0.12.0","0.11.1","0.11.0","0.10.0","0.9.0","0.8.0","0.7.0","0.6.0","0.5.0","0.4.0","0.3.0","0.2.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-49852.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}]}